This invention relates to a process for the preparation of aromatic cyanic acid esters having a free hydroxyl group, and to new aromatic cyanic acid esters.
It is known to react monophenols and polyphenols with cyanogen halides to give aromatic cyanic acid esters (German Published Specification No. 1,195,764) in which reaction all phenolic hydroxyl groups are esterified. Furthermore, it has been disclosed that this method however gives, starting from 2,6-di-tert.-butylhydroquinone or di-tert.-amylhydroquinone, the corresponding 1-hydroxy-2,6-di-tert.-butyl- or di-tert.amyl-phenyl (4)-cyanic acid ester, respectively, which is ascribed to the strong steric screening of the 1-hydroxyl group German Published Specification No. 2,155,413; C.R. Acad. Sc. Paris, 260 3,985 to 3,988), though aromatic cyanic acid esters were originally obtained from sterically hindered phenols (German Pat. No. 1,079,650).